Petri dish and improved cover therefor



Nov. 9, 1954 R. 1. FLETCHER 2,694,033

PETRI DISH AND IMPROVED COVER THEREFOR Filed May 4, 1953 Fig. /0

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BY (um Wavy I? PETRI DISH AND IIVIPRQVED COVER THEREFOR Robert I. Fletcher, Greencastle, Ind.

Application May 4, 1953, Serial No. 352,890 6 Claims. c1. 19's-,-1s9

The present invention relates to certain new and useful improvements in Petri dishes and has more particular reference to a structurally and functionally novel cover construction.

It has been found that bacteriology students and laboratory technicians often encounter perplexing dlfficulties in growing cultures in Petri dishes because accumulating condensate on the underside or bottom of the cover condenses and drips thus intermixing and alterably spoiling the culture. It is therefore the ob ect of the instant invention to solve this problem through the medium of a practical, economical and structurally distinct cover, one which utilizes principles of gravlty, flow and moisture absorption, in conjunction with each other.

Briefly summarized, the concept has to do with a Petri dish in which culture growth is contained and confined for study by students and laboratory technicians, said dish being of transparent glass and having a flat bottom and an upstanding marginal rim, and a readily applicable and removable transparent glass cover for the open top of said dish, the bottom of said cover having means for accumulating and absorbing condensate, whereby the latter is thus collected and controlled and is prevented from dripping and descending into an alterably intermixing and interfering with said culture growth.

Further novelty is predicated upon the stated structural means wherein only the central portion of the bottom is modified and this to a limited extent so that only a small area of the cover is obstructed, permitting the observer to see the culture at all times.

As will be later evidenced, the essence of the invention resides in the improved cover by itself, this being conventional in that it is of customary transparent glass construction, has a depending marginal capping and retaining flange and a flat top, the bottom being improved in that it has inclined gravity feeding surfaces to direct the condensate toward the center and is provided at the center with a depending stud, said stud serving as an adapter and retainer for a simple attachable and detachable disk of absorbent material, said disk having a sloti whereby the disk may be readily attached to the stu Other objects, features and advantages will become more readily apparent from the following description and the accompanying sheet of drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the views;

Figure 1 is a perspective view of the improved cover constructed in accordance with the principles of the present invention.

Figure 2 is a view in section showing the conventional Petri dish with the improved cover attached; and

Figure 3 is a perspective view of the readily attachable and detachable absorbent paper or equivalent disk or element.

Referring now to Figure 2, the dish proper is noted by the numeral 4 and has the usual circular fiat bottom 6, and upstanding endless marginal wall or socalled rim 8. The cover, as a unit, is noted by the numeral 10. Both dish and cover are constructed, as usual, of transparent glass.

As already emphasized the principal novelty resides, as is apparent, in the cover 10. This is a circular glass plate having a flat top 12 and a depending endless marginal flange 14 which fits, as usual, over the rim as brought out in Figure 2. One improvement has to States Patent do with the condensate collecting, accumulating and retaining media. While this may be of some other form it is here disclosed as being in the form of a simple absorbent paper disk, or the like, 16. This could be, if desired, a piece of blotting paper. It need not, however, be circular. It may vary in size. It. is preferably flat, however, and provided at its center with a slit or slot 18 by way of which it may be conveniently attached to and anchored on what is here called a depending axially centered stud'20. The latter is integral with the underside or bottom of the cover. The stud, of course, may vary in cross-section and size, the idea being that suitable means be carried by said bottom surface to allow the absorbent element 16 to be readily applied and removed, andwhen applied to lie or reside in intimate contact with the bottom, as brought out in Figure 2. The other feature has to do with the gradual increasing of the thickness of the glass on the underside toward the center and this provides the aforementioned inclined gravity feeding surfaces generally denoted at 22.

It will be clear therefore that the cover is preferably made of glass which is highly transparent with an inclined plane defining the so-called bottom or underneath surface, inclining at angle of at least one degree from the periphery toward the center. This arrangement permits the condensate to flow by gravity to the center of the cover. Any condensate formed on the bottom or underside of the cover will flow to the center and will be absorbed by the porous absorbent disk. This will permit clear vision of the surface of the bottom half or dish proper.

It is believed that a dish having the cover herein revealed constitutes a solution to the problem of satisfactorily coping with condensate which, when it mingles with the culture growth, gives a false impression to the observer.

The following advantages are worthy of attention, towit:

1. Only a small portion of the cover is covered permitting the observer to see the cultures at all times.

2. The absorbent material, preferably filter paper, can be sterilized with the entire dish and may be used over again.

3. The condensate resulting from the hot media being placed in the dish is retained for reabsorption by the media as it drys out.

4. The absorption of the condensate by the absorbent disk prohibits the condensate from dripping into the culture.

5. The inclined plane of my cover permits the condensate to flow to the absorbent disk by gravity thus clearing the area of the cover not covered by the disk of all condensate. This permits clear observation of the culture.

6. The invention can be used with any of the various sized Petri dish covers.

From the foregoing, the construction and operation of the device will be readily understood and further explanation is believed to be unnecessary. However, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the 1nvention to the exact construction shown and described, and accordingly all suitable modifications and equlvalents may be resorted to, falling within the scope of the appended claims.

What is claimed as new is as follows:

1. In combination, a Petri dish in which culture growth is contained and confined for study by students and laboratory technicians, said dish being of transparent glass and having a flat bottom and an upstanding marginal rim, and a readily applicable and removable transparent glass cover for the open top of said dish, the bottom of said cover being inclined and slanted downwardly toward the center of said cover and be 1 ng provided at said center with means for accumulatmg and absorbing condensate, whereby the latter is thus collected and controlled and is prevented from dripping and descending into and alterably intermixing and interfering with said culture growth.

2. As a new article of manufacture, a cover for a Petri dish comprising a transparent circular plate having a depending marginal flange the bottom of said cover slanting downwardly'frorn said flange toward the center of said cover and being provided at said center with a relatively small depending retainer stud,-and a centrally slitted absorbent element removablyfitted on said' stud, encircling the stud; and contacting said bot tom;

3; In combination, a- Petridish in which culture growth is contained and confined for study by students and laboratory technicians, said dishbeing of transparent glass and-having a flat bottom and an'upstand ing endless-marginal rim, a readily applicable and removable all transparent imperforate discoidal glass cover completely spanning and closing the 0pen-top of said dish, and absorbent means covering a limited surface of the center portion only of said bottom; said means serving to collect condensation-which accumulates at the center, whereby the condensate is thus collected and controlled and is' prevented from dripping and descending into and alterably intermixing and interfering withthe culture growth.

4. The structure defined in claim 3;- wherein' said means is a piece of absorbent materialof anareal'extent which is small in comparison to the over-all area of said bottom so as not to interfere with ready inspecuon of-the culture growth byway of said cover.

5. The structure defined in claim 3, wherein said bottom slants downwardly from the outer marginal portion" to" the" central portion" and wherein" said means is characterized by readily insertable and removable absorbent disk carried by the central portion only of said bottom, said disk being restricted in areal size so that only a small area of the cover is obstructed, permitting the observer to see the culture at all times.

6. As a new article of manufacture, a cover for a Petri dish comprising a transparent circular imperforate plate having a depending marginal flange, the bottom of said cover slanting downwardly from said fiange toward the center of said cover, this being accomplished by increasing the thickness of said circular plate from the peripheral marginal flange to the center, the center portion being provided with a relatively small depending retainer stud adapted to accommodate a readily attachable and detachable absorbent element.

References Cited in' the file ofthis patent UNITED STATES PATENTS Number Name Date 2,533,088 Brewer et'al Dec. 5, 1950 OTHER REFERENCES 85th Anniversary Catalog-Laboratory Apparatus and Supplies, Eimer and ,Amend-New York-received in Patent OfiiceApril'29; 1941, p'age273. 

2. AS A NEW ARTICLE OF MANUFACTURE, A COVER FOR A PETRI DISH COMPRISING A TRANSPARENT CIRCULAR PLATE HAVING A DEPENDING MARGINAL FLANGE THE BOTTOM OF SAID COVER SLANTING DOWNWARDLY FROM SAID FLANGE TOWARD THE CENTER OF SAID COVER AND BEING PROVIDED AT SAID CENTER WITH A RELATIVELY SMALL DEPENDING RETAINER STUD, AND A CENTRALLY SLITTED ABSORBENT ELEMENT REMOVABLY FITTED ON SAID STUD, ENCIRCLING THE STUD, AND CONTACTING SAID BOTTOM.
 3. IN COMBINATION, A PETRI DISH IN WHICH CULTURE GROWTH IS CONTAINED AND CONFINED FOR STUDY BY STUDENTS AND LABORATORY TECNICIANS, SAID DISH BEING OF TRANSPARENT GLASS AND HAVING A FLAT BOTTOM AND AN UPSTANDING ENDLESS MARGINAL RIM, A READILY APPLICABLE AND REMOVABLE ALL TRANSPARENT IMPERFORATE DISCOIDAL GLASS COVER COMPLETELY SPANNING AND CLOSING THE OPEN TOP OF SAID DISH, AND ABSORBENT MEANS COVERING A LIMITED SURFACE OF THE CENTER PORTION ONLY OF SAID BOTTOM, SAID MEANS SERVING TO COLLECT CONDENSATION WHICH ACCUMULATES AT THE CENTER, WHEREBY THE CONDENSATE IS THUS COLLECTED AND CONTROLLED AND IS PREVENTED FROM DRIPPING AND DESCENDING INTO AND ALTERABLY INTERMIXING AND INTERFERING WITH THE CULTURE GROWTH. 